Apparatus and method for generating a chemical precursor

ABSTRACT

Embodiments of an apparatus for generating a chemical precursor used in a vapor deposition processing system are provide which include a canister having a sidewall, a top, and a bottom forming an interior volume which is in fluid communication with an inlet port and an outlet port. The canister contains a plurality of baffles that extend from the bottom to an upper portion of the interior volume and form an extended mean flow path between the inlet port and the outlet port. In one embodiment, the baffles are contained on a prefabricated insert positioned on the bottom of the canister. In one example, an inlet tube may extend from the inlet port into the interior region and be positioned substantially parallel to the baffles. An outlet end of the inlet tube may be adapted to direct a gas flow away from the outlet port, such as towards the sidewall or top of the canister.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 11/119,681, filedMay 2, 2005, now U.S. Pat. No. 7,270,709, which is a continuation ofU.S. Ser. No. 10/447,255, filed May 27, 2003, issued as U.S. Pat. No.6,905,541, which is a continuation-in-part of U.S. Ser. No. 10/198,727,filed Jul. 17, 2002, now. U.S. Patent No. 7,186,385, which are allincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to apparatuses andprocesses for generating a chemical precursor that may be used during avapor deposition process.

2. Description of the Related Art

Reliably producing sub-micron and smaller features is one of the keytechnologies for the next generation of very large scale integration(VLSI) and ultra large scale integration (ULSI) of semiconductordevices. However, as the fringes of circuit technology are pressed, theshrinking dimensions of interconnects in VLSI and ULSI technology haveplaced additional demands on the processing capabilities. The multilevelinterconnects that lie at the heart of this technology require preciseprocessing of high aspect ratio features, such as vias and otherinterconnects. Reliable formation of these interconnects is veryimportant to VLSI and ULSI success and to the continued effort toincrease circuit density and quality of individual substrates.

As circuit densities increase, the widths of vias, contacts and otherfeatures, as well as the dielectric materials between them, decrease tosub-micron dimensions (e.g., about 0.20 micrometers or less), whereasthe thickness of the dielectric layers remains substantially constant,with the result that the aspect ratios for the features, i.e., theirheight divided by width, increase. Many traditional deposition processeshave difficulty filling sub-micron structures where the aspect ratioexceeds 4:1, and particularly where the aspect ratio exceeds 10:1.Therefore, there is a great amount of ongoing effort being directed atthe formation of substantially void-free and seam-free sub-micronfeatures having high aspect ratios.

Currently, copper and its alloys have become the metals of choice forsub-micron interconnect technology because copper has a lowerresistivity than aluminum, (about 1.7 μΩ-cm compared to about 3.1 μΩ-cmfor aluminum), and a higher current carrying capacity and significantlyhigher electromigration resistance. These characteristics are importantfor supporting the higher current densities experienced at high levelsof integration and increased device speed. Further, copper has a goodthermal conductivity and is available in a highly pure state.

Copper metallization can be achieved by a variety of techniques. Atypical method generally includes physical vapor depositing a barrierlayer over a feature, physical vapor depositing a copper seed layer overthe barrier layer, and then electroplating a copper conductive materiallayer over the copper seed layer to fill the feature. Finally, thedeposited layers and the dielectric layers are planarized, such as bychemical mechanical polishing (CMP), to define a conductive interconnectfeature.

However, one problem with the use of copper is that copper diffuses intosilicon, silicon dioxide, and other dielectric materials which maycompromise the integrity of devices. Therefore, conformal barrier layersbecome increasingly important to prevent copper diffusion. Tantalumnitride has been used as a barrier material to prevent the diffusion ofcopper into underlying layers. However, the chemicals used in thebarrier layer deposition, such as pentakis(dimethylamido)tantalum(PDMAT; Ta[N(CH₃)₂]₅), may include impurities that cause defects in thefabrication of semiconductor devices and reduce process yields.Therefore, there exists a need for a method of depositing a barrierlayer from a high-purity precursor.

SUMMARY OF THE INVENTION

Embodiments of the present invention include a method for filling afeature in a substrate. In one embodiment, the method includesdepositing a barrier layer formed from purifiedpentakis(dimethylamido)tantalum having less than about 5 ppm ofchlorine. The method additionally may include depositing a seed layerover the barrier layer and depositing a conductive layer over the seedlayer.

Embodiments of the present invention further include a canister forvaporizing PDMAT prior to depositing a tantalum nitride layer on asubstrate. The canister includes a sidewall, a top portion and a bottomportion. The canister contains an interior volume having an upper regionand a lower region. A heater surrounds the canister, in which the heatercreates a temperature gradient between the upper region and the lowerregion.

Embodiments of the present invention further include purifiedpentakis(dimethylamido)tantalum having less than about 5 ppm ofchlorine.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof, which are illustrated inthe appended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention, and aretherefore, not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 is a schematic cross-sectional view of one embodiment of abarrier layer formed over a substrate by atomic layer deposition (ALD);

FIGS. 2A-2C illustrate one embodiment of the alternating chemisorptionof monolayers of a tantalum containing compound and a nitrogencontaining compound on an exemplary portion of substrate;

FIG. 3 is a schematic cross-sectional view of one exemplary embodimentof a processing system that may be used to form one or more barrierlayers by atomic layer deposition;

FIG. 4A is a sectional side view of one embodiment of a gas generationcanister;

FIG. 4B is a sectional top view of another embodiment of a gasgeneration canister;

FIG. 4C is a sectional side view of another embodiment of a gasgeneration canister;

FIG. 5 is a sectional view of another embodiment of a gas generationcanister;

FIG. 6 is a sectional side view of another embodiment of a gasgeneration canister;

FIG. 7A illustrates a sectional view of a canister surrounded by acanister heater in accordance with one embodiment of the invention;

FIG. 7B illustrates a sectional view of a canister surrounded by acanister heater in accordance with another embodiment of the invention;and

FIG. 8 illustrates a sectional view of a canister containing a pluralityof solid particles in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a schematic cross-sectional view of one embodiment of asubstrate 100 having a dielectric layer 102 and a barrier layer 104deposited thereon. Depending on the processing stage, the substrate 100may be a silicon semiconductor substrate, or other material layer, whichhas been formed on the substrate. The dielectric layer 102 may be anoxide, a silicon oxide, carbon-silicon-oxide, a fluoro-silicon, a porousdielectric, or other suitable dielectric formed and patterned to providea contact hole or via 102H extending to an exposed surface portion 102Tof the substrate 100. For purposes of clarity, the substrate 100 refersto any work piece upon which film processing is performed, and asubstrate structure 150 is used to denote the substrate 100 as well asother material layers formed on the substrate 100, such as thedielectric layer 102. It is also understood by those with skill in theart that the present invention may be used in a dual damascene processflow. The barrier layer 104 is formed over the substrate structure 150of FIG. 1A by atomic layer deposition (ALD). Preferably, the barrierlayer includes a tantalum nitride layer.

In one aspect, atomic layer deposition of a tantalum nitride barrierlayer includes sequentially providing a tantalum containing compound anda nitrogen-containing compound to a process chamber. Sequentiallyproviding a tantalum containing compound and a nitrogen-containingcompound may result in the alternating chemisorption of monolayers of atantalum-containing compound and of monolayers of a nitrogen-containingcompound on the substrate structure 150.

FIGS. 2A-2C illustrate one embodiment of the alternating chemisorptionof monolayers of a tantalum containing compound and a nitrogencontaining compound on an exemplary portion of substrate 200 in a stageof integrated circuit fabrication, and more particularly at a stage ofbarrier layer formation. In FIG. 2A, a monolayer of a tantalumcontaining compound is chemisorbed on the substrate 200 by introducing apulse of the tantalum containing compound 205 into a process chamber.

The tantalum containing compound 205 typically includes tantalum atoms210 with one or more reactive species 215. In one embodiment, thetantalum containing compound is pentakis(dimethylamido)tantalum (PDMAT;Ta(NMe₂)₅). PDMAT may be advantageously used for a number of reasons.PDMAT is relatively stable. In addition, PDMAT has an adequate vaporpressure which makes it easy to deliver. In particular, PDMAT may beproduced with a low halide content. The halide content of PDMAT shouldbe produced with a halide content of less than 100 ppm. Not wishing tobe bound by theory, it is believed that an organometallic precursor witha low halide content is beneficial because halogens (such as chlorine)incorporated in the barrier layer may attack the copper layer depositedthereon.

Thermal decomposition of the PDMAT during production may causeimpurities in the PDMAT product, which is subsequently used to form thetantalum nitride barrier layer. The impurities may include compoundssuch as CH₃NTa(N(CH₃)₂)₃ and ((CH₃)₂N)₃Ta(NCH₂CH₃). In addition,reactions with moisture may result in tantalum oxo amide compounds inthe PDMAT product. Preferably, the tantalum oxo amide compounds areremoved from the PDMAT by sublimation. For example, the tantalum oxoamide compounds are removed in a bubbler. The PDMAT product preferablyhas less than about 5 ppm of chlorine. In addition, the levels oflithium, iron, fluorine, bromine, and iodine should be minimized. Mostpreferably, the total level of impurities is less than about 5 ppm.

The tantalum containing compound may be provided as a gas or may beprovided with the aid of a carrier gas. Examples of carrier gases whichmay be used include, but are not limited to, helium (He), argon (Ar),nitrogen (N₂), and hydrogen (H₂).

After the monolayer of the tantalum containing compound is chemisorbedonto the substrate 200, excess tantalum containing compound is removedfrom the process chamber by introducing a pulse of a purge gas thereto.Examples of purge gases which may be used include, but are not limitedto, helium (He), argon (Ar), nitrogen (N₂), hydrogen (H₂), and othergases.

Referring to FIG. 2B, after the process chamber has been purged, a pulseof a nitrogen containing compound 225 is introduced into the processchamber. The nitrogen containing compound 225 may be provided alone ormay be provided with the aid of a carrier gas. The nitrogen containingcompound 225 may comprise nitrogen atoms 230 with one or more reactivespecies 235. The nitrogen containing compound preferably includesammonia gas (NH₃). Other nitrogen containing compounds may be used whichinclude, but are not limited to, N_(x)H_(y) with x and y being integers(e.g., hydrazine (N₂H₄)), dimethyl hydrazine ((CH₃)₂N₂H₂),t-butylhydrazine (C₄H₉N₂H₃), phenylhydrazine (C₆H₅N₂H₃), other hydrazinederivatives, a nitrogen plasma source (e.g., N₂, N₂/H₂, NH₃, or a N₂H₄plasma), 2,2′-azotertbutane ((CH₃)₆C₂N₂), ethylazide (C₂H₅N₃), and othersuitable gases. A carrier gas may be used to deliver the nitrogencontaining compound if necessary.

A monolayer of the nitrogen containing compound 225 may be chemisorbedon the monolayer of the tantalum containing compound 205. Thecomposition and structure of precursors on a surface during atomic layerdeposition (ALD) is not precisely known. Not wishing to be bound bytheory, it is believed that the chemisorbed monolayer of the nitrogencontaining compound 225 reacts with the monolayer of the tantalumcontaining compound 205 to form a tantalum nitride layer 209. Thereactive species 215, 235 form by-products 240 that are transported fromthe substrate surface by the vacuum system.

After the monolayer of the nitrogen containing compound 225 ischemisorbed on the monolayer of the tantalum containing compound, anyexcess nitrogen containing compound is removed from the process chamberby introducing another pulse of the purge gas therein. Thereafter, asshown in FIG. 2C, the tantalum nitride layer deposition sequence ofalternating chemisorption of monolayers of the tantalum containingcompound and of the nitrogen containing compound may be repeated, ifnecessary, until a desired tantalum nitride thickness is achieved.

In FIGS. 2A-2C, the tantalum nitride layer formation is depicted asstarting with the chemisorption of a monolayer of a tantalum containingcompound on the substrate followed by a monolayer of a nitrogencontaining compound. Alternatively, the tantalum nitride layer formationmay start with the chemisorption of a monolayer of a nitrogen containingcompound on the substrate followed by a monolayer of the tantalumcontaining compound. Furthermore, in an alternative embodiment, a pumpevacuation alone between pulses of reactant gases may be used to preventmixing of the reactant gases.

The time duration for each pulse of the tantalum containing compound,the nitrogen containing compound, and the purge gas is variable anddepends on the volume capacity of a deposition chamber employed as wellas a vacuum system coupled thereto. For example, (1) a lower chamberpressure of a gas will require a longer pulse time; (2) a lower gas flowrate will require a longer time for chamber pressure to rise andstabilize requiring a longer pulse time; and (3) a large-volume chamberwill take longer to fill and will take longer for chamber pressure tostabilize thus requiring a longer pulse time. Similarly, time betweeneach pulse is also variable and depends on volume capacity of theprocess chamber as well as the vacuum system coupled thereto. Ingeneral, the time duration of a pulse of the tantalum containingcompound or the nitrogen containing compound should be long enough forchemisorption of a monolayer of the compound. In general, the pulse timeof the purge gas should be long enough to remove the reactionby-products and/or any residual materials remaining in the processchamber.

Generally, a pulse time of about 1.0 second or less for a tantalumcontaining compound and a pulse time of about 1.0 second or less for anitrogen containing compound are typically sufficient to chemisorbalternating monolayers on a substrate. A pulse time of about 1.0 secondor less for a purge gas is typically sufficient to remove reactionby-products as well as any residual materials remaining in the processchamber. Of course, a longer pulse time may be used to ensurechemisorption of the tantalum containing compound and the nitrogencontaining compound and to ensure removal of the reaction by-products.

During atomic layer deposition, the substrate may be maintainedapproximately below a thermal decomposition temperature of a selectedtantalum containing compound. An exemplary heater temperature range tobe used with tantalum containing compounds identified herein isapproximately between about 20° C. and about 500° C. at a chamberpressure less than about 100 Torr, preferably less than 50 Torr. Whenthe tantalum containing gas is PDMAT, the heater temperature ispreferably between about 100° C. and about 300° C., more preferablybetween about 175° C. and 250° C. In other embodiments, it should beunderstood that other temperatures may be used. For example, atemperature above a thermal decomposition temperature may be used.However, the temperature should be selected so that more than 50 percentof the deposition activity is by chemisorption processes. In anotherexample, a temperature above a thermal decomposition temperature may beused in which the amount of decomposition during each precursordeposition is limited so that the growth mode will be similar to anatomic layer deposition growth mode.

One exemplary process of depositing a tantalum nitride layer by atomiclayer deposition in a process chamber includes sequentially providingpentakis(dimethylamido)tantalum (PDMAT) at a flow rate between about 100sccm (standard cubic centimeters per minute) and about 1,000 sccm, andpreferably between about 200 sccm and 500 sccm, for a time period ofabout 1.0 second or less, providing ammonia at a flow rate between about100 sccm and about 1,000 sccm, preferably between about 200 sccm and 500sccm, for a time period of about 1.0 second or less, and a purge gas ata flow rate between about 100 sccm and about 1,000 sccm, preferablybetween about 200 sccm and 500 sccm for a time period of about 1.0second or less. The heater temperature preferably is maintained betweenabout 100° C. and about 300° C. at a chamber pressure between about 1.0and about 5.0 Torr. This process provides a tantalum nitride layer in athickness between about 0.5 Å and about 1.0 Å per cycle. The alternatingsequence may be repeated until a desired thickness is achieved.

FIG. 3 is a schematic cross-sectional view of one exemplary embodimentof a processing system 320 that may be used to form one or more barrierlayers by atomic layer deposition in accordance with aspects of thepresent invention. Of course, other processing systems may also be used.

The processing system 320 generally includes a processing chamber 306coupled to a gas delivery system 304. The processing chamber 306 may beany suitable processing chamber, for example, those available fromApplied Materials, Inc., located in Santa Clara, Calif. Exemplaryprocessing chambers include DPS CENTURA® etch chambers, PRODUCER®chemical vapor deposition chambers, and ENDURA® physical vapordeposition chambers, among others.

The gas delivery system 304 generally controls the rate and pressure atwhich various process and inert gases are delivered to the processingchamber 306. The number and types of process and other gases deliveredto the processing chamber 306 are generally selected based on theprocess to be performed in the processing chamber 306 coupled thereto.Although for simplicity a single gas delivery circuit is depicted in thegas delivery system 304 shown in FIG. 3, it is contemplated thatadditional gas delivery circuits may be utilized.

The gas delivery system 304 is generally coupled between a carrier gassource 302 and the processing chamber 306. The carrier gas source 302may be a local or remote vessel or a centralized facility source thatsupplies the carrier gas throughout the facility. The carrier gas source302 typically supplies a carrier gas such as argon, nitrogen, helium, orother inert or non-reactive gas.

The gas delivery system 304 typically includes a flow controller 310coupled between the carrier gas source 302 and a process gas sourcecanister 300. The flow controller 310 may be a proportional valve,modulating valve, needle valve, regulator, mass flow controller or thelike. One flow controller 310 that may be utilized is available fromSierra Instruments, Inc., located in Monterey, Calif.

The source canister 300 is typically coupled to and located between afirst and a second valve 312, 314. In one embodiment, the first andsecond valves 312, 314 are coupled to the source canister 300 and fittedwith disconnect fittings (not shown) to facilitate removal of the valves312, 314 with the source canister 300 from the gas delivery system 304.A third valve 316 is disposed between the second valve 314 and theprocessing chamber 306 to prevent introduction of contaminates into theprocessing chamber 306 after removal of the source canister 300 from thegas delivery system 304.

FIGS. 4A-4C depict sectional views of embodiments of the source canister300. The source canister 300 generally comprises an ampoule or othersealed container having a housing 420 that is adapted to hold precursormaterials 414 from which a process (or other) gas may be generatedthrough a sublimation or vaporization process. Some solid precursormaterials 414 that may generate a process gas in the source canister 300through a sublimation process include xenon difluoride, nickel carbonyl,tungsten hexacarbonyl, and pentakis(dimethylamido) tantalum (PDMAT),among others. Some liquid precursor materials 414 that may generate aprocess gas in the source canister 300 through a vaporization processinclude tetrakis(dimethylamido) titanium (TDMAT), tertbutylimidotris(diethylamido)tantalum (TBTDET), andpentakis(ethylmethylamido)tantalum (PEMAT), among others. The housing420 is generally fabricated from a material substantially inert to theprecursor materials 414 and gas produced therefrom, and thus, thematerial of construction may vary based on gas being produced.

The housing 420 may have any number of geometric forms. In theembodiment depicted in FIGS. 4A-4C, the housing 420 comprises acylindrical sidewall 402 and a bottom 432 sealed by a lid 404. The lid404 may be coupled to the sidewall 402 by welding, bonding, adhesives,or other leak-tight method. Alternately, the joint between the sidewall402 and the lid 404 may have a seal, o-ring, gasket, or the like,disposed therebetween to prevent leakage from the source canister 300.The sidewall 402 may alternatively comprise other hollow geometricforms, for example, a hollow square tube.

An inlet port 406 and an outlet port 408 are formed through the sourcecanister to allow gas flow into and out of the source canister 300. Theports 406, 408 may be formed through the lid 404 and/or sidewall 402 ofthe source canister 300. The ports 406, 408 are generally sealable toallow the interior of the source canister 300 to be isolated from thesurrounding environment during removal of the source canister 300 fromthe gas delivery system 304. In one embodiment, valves 312, 314 aresealingly coupled to ports 406, 408 to prevent leakage from the sourcecanister 300 when removed from the gas delivery system 304 (shown inFIG. 3) for recharging of the precursor material 414 or replacement ofthe source canister 300. Mating disconnect fittings 436A, 436B may becoupled to valves 312, 314 to facilitate removal and replacement of thesource canister 300 to and from the gas delivery system 304. Valves 312,314 are typically ball valves or other positive sealing valves thatallow the source canister 300 to be removed from the system efficientlyloaded and recycled while minimizing potential leakage from the sourcecanister 300 during filling, transport, or coupling to the gas deliverysystem 304. Alternatively, the source canister 300 can be refilledthrough a refill port 460 such as a small tube 464 with a VCR fitting462 disposed on the lid 404 of the source canister 300, as depicted inFIG. 4C.

The source canister 300 has an interior volume 438 having an upperregion 418 and a lower region 434. The lower region 434 of sourcecanister 300 is at least partially filled with the precursor materials414. Alternately, a liquid 416 may be added to a solid precursormaterial 414 to form a slurry 412. The precursor materials 414, theliquid 416, or the premixed slurry 412 may be introduced into sourcecanister 300 by removing the lid 404 or through one of the ports 406,408. The liquid 416 is selected such that the liquid 416 is non-reactivewith the precursor materials 414, that the precursor materials 414 areinsoluble therein, that the liquid 416 has a negligible vapor pressurecompared to the precursor materials 414, and that the ratio of the vaporpressure of the solid precursor material 414, e.g., tungstenhexacarbonyl, to that of the liquid 416 is greater than 103.

Precursor materials 414 mixed with the liquid 416 may be sporadicallyagitated to keep the precursor materials 414 suspended in the liquid 416in the slurry 412. In one embodiment, precursor materials 414 and theliquid 416 are agitated by a magnetic stirrer 440. The magnetic stirrer440 includes a magnetic motor 442 disposed beneath the bottom 432 of thesource canister 300 and a magnetic pill 444 disposed in the lower region434 of the source canister 300. The magnetic motor 442 operates torotate the magnetic pill 444 within the source canister 300, therebymixing the slurry 412. The magnetic pill 444 should have an outercoating of material that is a non-reactive with the precursor materials414, the liquid 416, or the source canister 300. Suitable magneticmixers are commercially available. One example of a suitable magneticmixer is IKAMAG® REO available from IKA® Works in Wilmington, N.C.Alternatively, the slurry 412 may be agitated other means, such as by amixer, a bubbler, or the like.

The agitation of the liquid 416 may induce droplets of the liquid 416 tobecome entrained in the carrier gas and carried toward the processingchamber 306. To prevent such droplets of liquid 416 from reaching theprocessing chamber 306, an oil trap 450 may optionally be coupled to theexit port 408 of the source canister 300. The oil trap 450 includes abody 452 containing a plurality of interleaved baffles 454 which extendpast a centerline 456 of the oil trap body 452 and are angled at leastslightly downward towards the source canister 300. The baffles 454 forcethe gas flowing towards the processing chamber 306 to flow a tortuouspath around the baffles 454. The surface area of the baffles 454provides a large surface area exposed to the flowing gas to which oildroplets that may be entrained in the gas adhere. The downward angle ofthe baffles 454 allows any oil accumulated in the oil trap to flowdownward and back into the source canister 300.

The source canister 300 includes at least one baffle 410 disposed withinthe upper region 418 of the source canister 300, per one embodimentdepicted in FIG. 4A. The baffle 410 is disposed between inlet port 406and outlet port 408, creating an extended mean flow path, therebypreventing direct (i.e., straight line) flow of the carrier gas from theinlet port 406 to the outlet port 408. This has the effect of increasingthe mean dwell time of the carrier gas in the source canister 300 andincreasing the quantity of sublimated or vaporized precursor gas carriedby the carrier gas. Additionally, the baffles 410 direct the carrier gasover the entire exposed surface of the precursor material 414 disposedin the source canister 300, ensuring repeatable gas generationcharacteristics and efficient consumption of the precursor material 414.

The number, spacing, and shape of the baffles 410 may be selected totune the source canister 300 for optimum generation of precursor gas.For example, a greater number of baffles 410 may be selected to imparthigher carrier gas velocities at the precursor material 414 or the shapeof the baffles 410 may be configured to control the consumption of theprecursor material 414 for more efficient usage of the precursormaterial.

The baffle 410 may be attached to the sidewall 402 (FIG. 4B), the lid404 (FIG. 4A), or the baffle 410 may be a prefabricated insert 413designed to fit within the source canister 300 (FIG. 4C). In oneembodiment, the baffles 410 disposed in the source canister 300 comprisefive rectangular plates fabricated of the same material as the sidewall402. Referring to FIG. 4B, the baffles 410 are welded or otherwisefastened to the sidewall 402 parallel to each other. The baffles 410 areinterleaved, fastened to opposing sides of the source canister in analternating fashion, such that a serpentine extended mean flow path iscreated. Furthermore, the baffles 410 are situated between the inletport 406 and the outlet port 408 on the lid 404 when placed on thesidewall 402 and are disposed such that there is no air space betweenthe baffles 410 and the lid 404. The baffles 410 additionally extend atleast partially into the lower region 434 of the source canister 300,thus defining an extended mean flow path for the carrier gas flowingthrough the upper region 418.

Optionally, an inlet tube 422 may be disposed in the interior volume 438of the source canister 300. The tube 422 is coupled by a first end 424to the inlet port 406 of the source canister 300 and terminates at asecond end 426 in the upper region 418 of the source canister 300. Thetube 422 injects the carrier gas into the upper region 418 of the sourcecanister 300 at a location closer to the precursor materials 414 or theslurry 412.

The precursor materials 414 generate a precursor gas at a predefinedtemperature and pressure. Sublimating or vaporized gas from theprecursor materials 414 accumulate in the upper region 418 of the sourcecanister 300 and are swept out by an inert carrier gas entering throughinlet port 406 and exiting outlet port 408 to be carried to theprocessing chamber 306. In one embodiment, the precursor materials 414are heated to a predefined temperature by a resistive heater 430disposed proximate to the sidewall 402. Alternately, the precursormaterials 414 may be heated by other means, such as by a cartridgeheater (not shown) disposed in the upper region 418 or the lower region434 of the source canister 300 or by preheating the carrier gas with aheater (not shown) placed upstream of the carrier gas inlet port 406. Tomaximize uniform heat distribution throughout the slurry 412, the liquid416 and the baffles 410 should be good conductors of heat.

In accordance with yet another embodiment of the invention, a pluralityof solid beads or particles 810 with high thermal conductivity, such as,aluminum nitride or boron nitride, may be used in lieu of the liquid416, as shown in FIG. 8. Such solid particles 810 may be used totransfer more heat from the sidewall of the canister 800 to theprecursor materials 414 than the liquid 416. The solid particles 810have the same properties as the liquid 416 in that they are non-reactivewith the precursor materials 414, insoluble, have a negligible vaporpressure compared to the precursor materials 414. As such, the solidparticles 810 are configured to efficiently transfer heat from thesidewall of the canister 800 to the center portion of the canister 800,thereby leading to more precursor material utilization duringsublimation or vaporization. The solid particles 810 may also bedegassed and cleaned from contaminants, water vapor and the like, priorto being deposited into the canister 800.

In one exemplary mode of operation, the lower region 434 of the sourcecanister 300 is at least partially filled with a mixture of tungstenhexacarbonyl and diffusion pump oil to form the slurry 412. The slurry412 is held at a pressure of about 5 Torr and is heated to a temperaturein the range of about 40° C. to about 50° C. by a resistive heater 430located proximate to the source canister 300. Carrier gas in the form ofargon is flowed through inlet port 406 into the upper region 418 at arate of about 400 sccm. The argon flows in an extended mean flow pathdefined by the torturous path through the baffles 410 before exiting thesource canister 300 through outlet port 408, advantageously increasingthe mean dwell time of the argon in the upper region 418 of the sourcecanister 300. The increased dwell time in the source canister 300advantageously increases the saturation level of sublimated tungstenhexacarbonyl vapors within the carrier gas. Moreover, the torturous paththrough the baffles 410 advantageously exposes the substantially all ofthe exposed surface area of the precursor material 414 to the carriergas flow for uniform consumption of the precursor material 414 andgeneration of the precursor gas.

FIGS. 7A-7B illustrate other embodiments for heating the precursormaterials 414. More specifically, FIGS. 7A-7B illustrate a sectionalview of a canister 700 surrounded by a canister heater 730, which isconfigured to create a temperature gradient between a lower region 434of the canister 700 and an upper region 418 of the canister 700 with thelower region 434 being the coldest region and the upper region 418 beingthe hottest region. The temperature gradient may range from about 5° C.to about 15° C. Since solid precursor materials generally tend toaccumulate or condense at the coldest region of the canister 700, thecanister heater 730 is configured to ensure that the solid precursormaterials 414 will accumulate at the lower region 434 of the canister700, thereby increasing the predictability of where the solid precursormaterials 414 will condense and the temperature of the solid precursormaterials 414. The canister heater 730 includes a heating element 750disposed inside the canister heater 730 such that the entire canister700, including the upper region 418 and the lower region 434, is heatedby the canister heater 730. The heating element 750 near the upperregion 418 may be configured to generate more heat than the heatingelement 750 near the lower region 434, thereby allowing the canisterheater 730 to create the temperature gradient between the lower region434 and the upper region 418. In one embodiment, the heating element 750is configured such that the temperature at the upper region 418 isbetween about 5° C. to about 15° C. higher than the temperature at thelower region 434. In another embodiment, the heating element 750 isconfigured such that the temperature at the upper region 418 is about70° C., the temperature at the lower region 434 is about 60° C. and thetemperature at the sidewall of the canister 700 is about 65° C. Thepower of the heating element 730 may be about 600 watts at 208 VACinput.

The canister heater 730 may also include a cooling plate positioned atthe bottom of the canister heater 730 to further ensure that the coldestregion of the canister 700 is the lower region 434, and thereby ensuringthat the solid precursor materials 414 condense at the lower region 434.Further, the valves 312, 314, the oil trap 450, the inlet port 406 andthe exit port 408 may be heated with a resistive heating tape. Since theupper region 418 is configured to have a higher temperature than thelower region 434, the baffles 410 may be used to transfer heat from theupper region 418 to the lower region 434, thereby allowing the canisterheater 730 to maintain the desired temperature gradient. Embodiments ofthe invention also contemplate other heat transfer mediums, such as,silos 710 extending from the bottom portion 432 of the canister 700 tothe upper region 418, as depicted in FIG. 7B.

FIG. 5 depicts a sectional view of another embodiment of a canister 500for generating a process gas. The canister 500 includes a sidewall 402,a lid 404 and a bottom 432 enclosing an interior volume 438. At leastone of the lid 404 or sidewall 402 contains an inlet port 406 and anoutlet port 408 for gas entry and egress. The interior volume 438 of thecanister 500 is split into an upper region 418 and a lower region 434.Precursor materials 414 at least partially fill the lower region 434.The precursor materials 414 may be in the form of a solid, liquid, orslurry, and are adapted to generate a process gas by sublimation and/orvaporization.

A tube 502 is disposed in the interior volume 438 of the canister 500and is adapted to direct a flow of gas within the canister 500 away fromthe precursor materials 414, advantageously preventing gas flowing outof the tube 502 from directly impinging the precursor materials 414 andcausing particulates to become airborne and carried through the outletport 408 and into the processing chamber 306. The tube 502 is coupled ata first end 504 to the inlet port 406. The tube 502 extends from thefirst end 504 to a second end 526A that is positioned in the upperregion 418 above the precursor materials 414. The second end 526A may beadapted to direct the flow of gas toward the sidewall 402, thuspreventing direct (linear or line of sight) flow of the gas through thecanister 500 between the ports 406, 408, creating an extended mean flowpath.

In one embodiment, an outlet 506 of the second end 526A of the tube 502is oriented at an angle of about 15° to about 90° relative to a centeraxis 508 of the canister 500. In another embodiment, the tube 502 has a‘J’-shaped second end 526B that directs the flow of gas exiting theoutlet 506 towards the lid 404 of the canister 500. In anotherembodiment, the tube 502 has a capped second end 526C having a plug orcap 510 closing the end of the tube 502. The capped second end 526C hasat least one opening 528 formed in the side of the tube 502 proximatethe cap 510. Gas, exiting the openings 528, is typically directedperpendicular to the center axis 508 and away from the precursormaterials 414 disposed in the lower region 434 of the canister 500.Optionally, at least one baffle 410 (shown in phantom) as describedabove may be disposed within the chamber 500 and utilized in tandem withany of the embodiments of the tube 502 described above.

In one exemplary mode of operation, the lower region 434 of the canister500 is at least partially filled with a mixture of tungsten hexacarbonyland diffusion pump oil to form the slurry 412. The slurry 412 is held ata pressure of about 5 Torr and is heated to a temperature in the rangeof about 40° C. to about 50° C. by a resistive heater 430 locatedproximate to the canister 500. A carrier gas in the form of argon isflowed through the inlet port 406 and the tube 502 into the upper region418 at a rate of about 200 sccm. The second end 526A of the tube 502directs the flow of the carrier gas in an extended mean flow path awayfrom the outlet port 408, advantageously increasing the mean dwell timeof the argon in the upper region 418 of the canister 500 and preventingdirect flow of carrier gas upon the precursor materials 414 to minimizeparticulate generation. The increased dwell time in the canister 500advantageously increases the saturation level of sublimated tungstenhexacarbonyl gas within the carrier gas while the decrease inparticulate generation improves product yields, conserves source solids,and reduces downstream contamination.

FIG. 6 depicts a sectional view of another embodiment of a canister 600for generating a precursor gas. The canister 600 includes a sidewall402, a lid 404, and a bottom 432 enclosing an interior volume 438. Atleast one of the lid 404 or sidewall 402 contains an inlet port 406 andan outlet port 408 for gas entry and egress. Inlet and outlet ports 406,408 are coupled to valves 312, 314 fitted with mating disconnectfittings 436A, 436B to facilitate removal of the canister 600 from thegas delivery system 304. Optionally, an oil trap 450 is coupled betweenthe outlet port 408 and the valve 314 to capture any oil particulatethat may be present in the gas flowing to the process chamber 306.

The interior volume 438 of the canister 600 is split into an upperregion 418 and a lower region 434. Precursor materials 414 and a liquid416 at least partially fill the lower region 434. A tube 602 is disposedin the interior volume 438 of the canister 600 and is adapted to directa first gas flow F₁ within the canister 600 away from the precursormaterial and liquid mixture and to direct a second gas flow F₂ throughthe mixture. The flow F₁ is much greater than the flow F₂. The flow F₂is configured to act as a bubbler, being great enough to agitate theprecursor material and liquid mixture but not enough to cause particlesor droplets of the precursor materials 414 or liquid 416 from becomingairborne. Thus, this embodiment advantageously agitates the precursormaterial and liquid mixture while minimizing particulates produced dueto direct impingement of the gas flowing out of the tube 602 on theprecursor materials 414 from becoming airborne and carried through theoutlet port 408 and into the processing chamber 306.

The tube 602 is coupled at a first end 604 to the inlet port 406. Thetube 602 extends from the first end 604 to a second end 606 that ispositioned in the lower region 434 of the canister 600, within theprecursor material and liquid mixture. The tube 602 has an opening 608disposed in the upper region 418 of the canister 600 that directs thefirst gas flow F₁ towards a sidewall 402 of the canister 600. The tube600 has a restriction 610 disposed in the upper region 438 of thecanister 600 located below the opening 608. The restriction 610 servesto decrease the second gas flow F₂ flowing toward the second end 606 ofthe tube 602 and into the slurry 412. By adjusting the amount of therestriction, the relative rates of the first and second gas flows F₁ andF₂ can be regulated. This regulation serves at least two purposes.First, the second gas flow F₂ can be minimized to provide just enoughagitation to maintain suspension or mixing of the precursor materials414 in the liquid 416 while minimizing particulate generation andpotential contamination of the processing chamber 306. Second, the firstgas flow F₁ can be regulated to maintain the overall flow volumenecessary to provide the required quantity of sublimated and/or vaporsfrom the precursor materials 414 to the processing chamber 306.

Optionally, an at least one baffle 410 as described above may bedisposed within the canister 600 and utilized in tandem with any of theembodiments of the tube 602 described above.

While foregoing is directed to the preferred embodiment of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An apparatus for generating a chemical precursor used in a vapordeposition processing system, comprising: a canister having a sidewall,a top, and a bottom providing an interior volume; a precursor materialat least partially filling the interior volume of the canister; an inletport and an outlet port in fluid communication with the interior volume;and a plurality of silos within the interior volume, wherein the silosextend from the bottom and form an extended mean flow path between theinlet port and the outlet port.
 2. The apparatus of claim 1, wherein thesilos extend from the bottom of the canister to an upper portion of theinterior volume.
 3. The apparatus of claim 1, wherein the silos arebaffles.
 4. The apparatus of claim 3, wherein the baffles comprise ofrectangular plates.
 5. The apparatus of claim 3, wherein the baffles area prefabricated insert positioned on the bottom of the canister.
 6. Theapparatus of claim 5, wherein the baffles extend into an upper portionof the interior volume.
 7. The apparatus of claim 1, wherein an inlettube extends from the inlet port into the canister.
 8. The apparatus ofclaim 7, wherein the inlet tube extends from the inlet port to a lowerregion of the interior region.
 9. The apparatus of claim 7, wherein thesilos are positioned substantially parallel to the inlet tube.
 10. Theapparatus of claim 7, wherein the silos extend from the bottom of thecanister to an upper portion of the interior volume.
 11. The apparatusof claim 7, wherein the inlet tube comprises an outlet end within theinterior region.
 12. The apparatus of claim 11, wherein the outlet endis adapted to direct a gas flow towards the sidewall of the canister.13. The apparatus of claim 11, wherein the outlet end is adapted todirect a gas flow towards the top of the canister.
 14. The apparatus ofclaim 11, wherein the outlet end is adapted to direct a gas flow awayfrom the outlet port.
 15. The apparatus of claim 1, wherein a heater iscoupled to the canister.
 16. The apparatus of claim 15, wherein theheater is disposed proximate the sidewall of the canister, the top ofthe canister, the bottom of the canister, or combinations thereof. 17.The apparatus of claim 1, wherein the canister comprises a heat transfermedium within the interior volume.
 18. The apparatus of claim 17,wherein the heat transfer medium is at least one of the silos.
 19. Theapparatus of claim 17, wherein the heat transfer medium is a pluralityof solid particles at least partially filling the interior volume. 20.The apparatus of claim 19, wherein the solid particles aremetal-containing particles.
 21. The apparatus of claim 19, wherein thesolid particles comprise a material selected from the group consistingof aluminum nitride, boron nitride, derivatives thereof, andcombinations thereof.
 22. The apparatus of claim 1, wherein theprecursor material is a tantalum precursor.
 23. The apparatus of claim22, wherein the precursor material is pentakis(dimethylamido) tantalum.24. The apparatus of claim 22, wherein the precursor material compriseschlorine impurities of less than 5 ppm.
 25. An apparatus for generatinga chemical precursor used in a vapor deposition processing system,comprising: a canister having a sidewall, a top, and a bottom providingan interior volumes, wherein the canister comprises a plurality of solidparticles at least partially filing the interior volume; an inlet portand an outlet port in fluid communication with the interior volume; aninlet tube extending from the inlet port into the canister; and aplurality of baffles within the interior volume, wherein the bafflesextend from the bottom.
 26. The apparatus of claim 25, wherein thebaffles form an extended mean flow path between the inlet port and theoutlet port.
 27. The apparatus of claim 25, wherein the baffles compriseof rectangular plates.
 28. The apparatus of claim 25, wherein thebaffles are silos.
 29. The apparatus of claim 28, wherein the silosextend from the bottom of the canister to an upper portion of theinterior volume.
 30. The apparatus of claim 25, wherein the baffles area prefabricated insert positioned on the bottom of the canister.
 31. Theapparatus of claim 30, wherein the baffles extend into an upper portionof the interior volume.
 32. The apparatus of claim 25, wherein the inlettube extends from the inlet port to a lower region of the interiorregion.
 33. The apparatus of claim 32, wherein the baffles arepositioned substantially parallel to the inlet tube.
 34. The apparatusof claim 32, wherein the inlet tube comprises an outlet end within theinterior region.
 35. The apparatus of claim 34, wherein the outlet endis adapted to direct a gas flow towards the sidewall of the canister.36. The apparatus of claim 34, wherein the outlet end is adapted todirect a gas flow towards the top of the canister.
 37. The apparatus ofclaim 34, wherein the outlet end is adapted to direct a gas flow awayfrom the outlet port.
 38. The apparatus of claim 25, wherein the solidparticles are metal-containing particles.
 39. The apparatus of claim 38,wherein the canister further contains a tantalum precursor.
 40. Theapparatus of claim 39, wherein the tantalum precursor is pentakis(dimethylamido) tantalum.
 41. The apparatus of claim 39, wherein thetantalum precursor and metal-containing particles form a precursormixture.
 42. An apparatus for generating a chemical precursor used in avapor deposition processing system, comprising: a canister having asidewall, a top, and a bottom providing an interior volume, wherein thecanister comprises a plurality of solid particles at least partiallyfilling the interior volume; an inlet port and an outlet port in fluidcommunication with the interior volume; an inlet tube extending from theinlet port into the canister; and a prefabricated insert positioned onthe bottom of the canister and comprising a plurality of baffles. 43.The apparatus of claim 42, wherein the baffles form an extended meanflow path between the inlet port and the outlet port and extend from thebottom of the canister to an upper portion of the interior volume. 44.The apparatus of claim 42, wherein the solid particles aremetal-containing particles.
 45. The apparatus of claim 44, furthercomprising a tantalum precursor.
 46. The apparatus of claim 45, whereinthe tantalum precursor is pentakis(dimethylamido) tantalum.
 47. Theapparatus of claim 45, wherein the tantalum precursor andmetal-containing particles form a precursor mixture.
 48. An apparatusfor generating a chemical precursor used in a vapor depositionprocessing system, comprising: a canister containing an interior volumeand having a bottom surface therein; an inlet port and an outlet port influid communication with the interior volume; an inlet tube extendingfrom the inlet port into the canister; a plurality of baffles extendingfrom the bottom surface; and a precursor mixture comprising a tantalumprecursor and a plurality of metal-containing particles, wherein theprecursor mixture at least partially fills the interior volume.
 49. Theapparatus of claim 48, wherein the tantalum precursor ispentakis(dimethylamido) tantalum.
 50. An apparatus for generating achemical precursor used in a vapor deposition processing system,comprising: a canister containing an interior volume and having a bottomsurface therein; an inlet port and an outlet port in fluid communicationwith the interior volume; an inlet tube extending from the inlet portinto the canister; a prefabricated insert positioned within the canisterand comprising a plurality of baffles extending from the bottom surface;and a precursor mixture comprising a tantalum precursor and a pluralityof metal-containing particles, wherein the precursor mixture at leastpartially fills the interior volume.
 51. The apparatus of claim 50,wherein the tantalum precursor is pentakis(dimethylamido) tantalum.